This invention relates to a panel assembly and is particularly, though not exclusively, concerned with an assembly comprising a heater and/or cooker panel adhesively secured to a surrounding frame and/or mounting.
German Gebrauchsmuster Nos. 7401645 and 7406676 disclose cooker hobs wherein the cooking panel or hob plate is adhesively secured inside a frame surround by means of a permanently elastic, thermostable adhesive material. A common feature in these arrangements is that the frame surround does not overlap the hob plate and that the hob plate is adhesively secured to an internal flange provided below the hob plate, the internal flange being provided as an integral part of a continuously extruded profile from which the frame is formed. The arrangement is such that the upper surface of the hob plate is either flush with or about 1-2 mm below the exposed upper edge of the frame.
A gap is provided between the sides of the hob plate and the inner surface of the frame and this is sealed with a permanently elastic sealant. In practice, arrangements of the above described type have the disadvantage that they impose restrictions on the choice of material which can be used in the manufacture of the frame as well as having a relatively narrow field of practical application. For instance, it is a serious drawback that only materials which have a surface quality which enables a good, durable and mechanically firm bond with the adhesive can be used for the frame part. Since anodized or plastic coated surfaces, for example, tend to have poor and mostly indifferent adhesion to silicone adhesives, such materials cannot be used with advantage for making frame surrounds for use in the above described arrangement because a firm, durable bond cannot be guaranteed. The same applies to the use of such materials to form mounting elements used for mounting the hob plate. A further disadvantage of the above described arrangement is that there is a restricted freedom of choice with regard to the configuration of the profile for the frame parts in view of the intended use. For example, while enameled surfaces are very well suited for adhesive securement by means of permanently elastic silicone adhesives, it is impractical to enamel edges which have a small radius of curvature because such edges are highly sensitive to knocks. Consequently, enameled frames with exposed edges are virtually excluded from consideration because the enamel tends to chip off very easily at the curved edges where the radius of the curvature is small, when subject to blows or knocks.
Lastly, there is also a limit to the ability of plastic profiles or of plastic-coated metal profiles to withstand thermal stresses. Adhesive joints can, therefore, be used with frames having such profiles only to a limited extent where the adhesive joint itself would be subjected to unduly high temperatures even though these would still be tolerated by the adhesive itself. Consequently, no plastic frames having such profiles can be used for high heat resistant applications.